Nonfreezing radiator



ea. 19, 1944, M. 5. SMITH NONFREEZING RADIATOR Filed April 16, 1942 2 Sheets-Sheet l W M a ma N V .mm M M ATTORN EY ec. i9, 144. M. 5. SMITH 2,365,497

NONFREEZING RADIATOR Filed April '16, 1942 2 Sheets-Sheet 2 Patented Dec. 19, 1944' nomanzmo RADIATOR I Milton s. Smith, Maplewood, N. 1., asslgnor to Buensod-Stacey, Incorporated, a corporation of Delaware Application April 16, 1942, Serial No. 439,191

7 Claim.

This invention relates to heating apparatus, and is particularly concerned with the improvement of radiating equipment for use in steamheating systems of buildings and the like.

The principal object of the invention is to provide a steam-condensing radiator which may safely be employed to temper air drawn into a building from the outside to fulfill ventilation requirements, for example, or for some other service under which the radiator may be called upon to heat air passing over its surfaces at a temperature of less than 32 F. when steam is being supplied in less than full-load quantity, an operating condition which would freeze condensate in and destroy the tubes of a radiator of conventional design and construction.

It is another object of the invention to provide a radiator, and especially one of the extended surface class, with means for supplying steam to it in quantities modulated in accordance with actual heating requirements, and with other means which serve to prevent freezing of condensate in its tubes under substantially any condition which-may be met in the normal use of the radiator.

It is a more specific object of the invention to provide a radiator of the foregoing kind with means for warming condensate in its main heattransfer tubes, which means are adapted to operate independently of the steam supplied to the main tubes so as to maintain the condensate in the main transfer tubes at a temperature above 32 F. even though the outer surfaces of those main tubes may be at a lesser temperature.

The foregoing and other objects of the invention, as well as various features thereof, may be better understood from a consideration of the following description when read in the light of the accompanying drawings, in which-- Figure 1 is a plan view of a fragment of an extended surface radiator embodying the invention, with certain parts broken away in order better to show the interior construction;

Fig. 2 is a sectional view taken on the line 22 of Fig. 1;

Fig; 3 is a sectional view of a fragment of a radiator similar to Fig. 2, but illustrating the application of the invention thereto in a slightly different way;

Fig. 4 is a side elevational view of another form of radiator in which the invention is embodied;

and

having their outer surfaces greatly extended by the application of closely spaced metal fins II. and their opposite ends connected to opposed steam supply and condensate discharge headers l2 and I3; and a casing ll supporting these various parts and serving to direct a stream of air over the finned surfaces of the tubes while preventing the by-passing of that air around the headers. It is conventional to bend each of the tubes It at one or more points in the manner shown so that they may expand and contract independently one of another without placing undue strain upon themselves or their joints with the headers. The length of the tubes will, of course, depend upon the size and capacity of the particular unit of which they are parts, and it is not at all unusual for them to be six, eight, or even twelve feet long.

It will be assumed, for purposes of description, that the radiator- 9 is employed for tempering air drawn into a building from the outside to fulfill ventilation requirements therein. In this service it is obvious that the radiator will frequently be called upon to warm the entering air from an initial temperature of less than 32 F. to some desired final value, and that the range of sub-freezing temperature which will be encountered in ordinary usage may be fairly great. The radiator must, therefore, have sufficient capacity to carry the heating load under the lowest expected minimum temperature, which in many localities may be well below zero F. In order to avoid wasteful overheating when the temperature of the entering air rises above the expected minimum, an automatic throttling valve, indicated diagrammatically at [5, is included in the supply line It (also indicated diagrammatically) to header l2; and is operatively connected to a thermostat "l1 or other wellknown control means so that it may respond to changes in temperature in the heated space and increase or decrease the steam supply in accordance with actual heating needs. It is apparent that when the unit is operated under a throttled condition, its radiating surface greatly exceeds that needed to condense the quantity of steam actually supplied. There are many instances, for example, when the entire quantity of steam delivered to header 12 will be condensed within the first few feet of tubes l0, leaving their remaining portions unheated and substantially at the temperature of air which is passing over them. If, under these circumstances. the entering air is at a temperature of less than 32 F., though still above the expected minimum, it may very well freeze the condensate in the tubes l0 and burst those elements. I

In order to prevent freezing-up of the radiator when it is subjected to an operating condition such as that outlined above, it is provided, in

accordance with the invention, with a series of small tubes it, each of which is located substantially centrally of a main tube i and ex-v tends for the full length thereof with one of its ends passing through the wall of the supply header at l8 and its other end through the discharge header at 20; and the opposite ends of all of these secondary tubes are joined to auxiliary supply and discharge headers 2|, 22, of which the former is connectedto an appropriate source of steam under substantially constant pressure, and the latter to the condensate drain line which is indicated diagrammatically at 23. It is usually desirable that the smaller tubes be disposed out of contact with the inner surface of the main tubes, and supports 25 (Fig. 5) may accordingly be applied at one or more points intermediate the ends of the small tubes for this purpose. Any suitable form of support may be employed, the ones shown having the advantage of simplicity and of occupying a minimum amount of space within the main tubes. Preferably, auxiliary header 2| is connected by line 24 tothe main steam supply line i6 at a point full-load conditions in a perfectly normal way.

Thus when steam is supplied to the inlet header [2 at full-line pressure, it .passes directly into and forces its way completely through the main tubes iii. In such circumstances the tubes are maintained substantially filled with steam, and condensate can drain directly from them into the discharge header I3 without any possibility of freezing. The smaller tubes it do not material- 1y interfere with this operation, but merely occupy a small cross-sectional area of the main tubes, and at this time perform little or no function. Steam will be present in the secondary tubes, of course, but it will be surrounded by the steam at substantially the same temperature and pressure in the main tubes, and, accordingly, under full-load operating conditions there will be little or no condensation in the secondary tubes, and little or no flow of steam through them.

The primary function of the small tubes i8 is to provide a constant source of heat extending throughout the length of the main tubes for the purpose of warming condensate in the latter when the heater is being operated with a throttled steam supply. If it be assumed, for example, that air is flowing over the surfaces of the main tubes at a temperature of about 25 F.--a point much above the design minimum but below freezing--and that the valve I5 has been actuated to throttle the supply of steam to header II in accordance with actual heating requirements, then all of that steam passing through valve will be condensed within the first few feet of the tubes Hi. It is not present in suillcient quantity, nor is the pressure great enough, to force the steam beyond, say, the midpoint of the tubes. The resulting condensate will therefore have to flow through several feet of the tubes before it can reach the discharge header. During that time it is in intimate heattransfer relation with air at a temperature of 25 F., a condition which if existing in a radiator .of a standard design and construction would surely result in the freezing of the condensate and the bursting of the tubes. In the radiator of the invention, however, the small tubes 88 are filled with steam under full-line pressure from source l8 and will supply enough heat to the condensate to warm it sufllciently to prevent freezing. The actual size of the small tubes 18 cannot be stated with precision because it will vary with radiators of diiferent sizes and various; designs, and will depend to some extent upon the service to which the radiator is to be put. It sufilces to say, however, that secondary tubes of from V to of the cross-sectional area of the main tubes should serve to maintain the condensate in the main tubes at a temperature above freezing under almost any operating condition which will be met in actual usagel In a radiator constructed in accordance with the invention, the condensate in the mam tubes can continue to flow toward the primary discharge header despite the fact that the outer surfaces of those main tubes may be well below freezing.

In the form of the invention illustrated in Fig. 1 it is essential that the openings l9 and 26 m the headers l2 and I8, through which tubes 58 pass, shall be sealed to prevent the escape of steam or condensate from the primary headers at these points. This may readily be accomplished by forming suitable nipples 2t and it upon the rear surface of headers i2 and til, within which nipplesthe small tubes may be soldered; and similar nipples 28, 29 are provided on the auxiliary headers 2|, 22 to receive the open ends of the small tubes. Any other suitable arrangement for sealing the openings in the primary headers, and for securing the ends of the small tubes to the auxiliary headers, may, however, be employed.

The invention is illustrated in another form in Fig. 3 where, for purposes of convenience, it will be assumed that main tubes Mia and secondary tubes lBa are substantially identical with the like parts of the device of Figs. 1 and 2. In this form of the invention th auxiliary supply header 2ia is constructed as a part of the primary header l2a, and the auxiliary discharge header 22a is similarly embodied as a part of the primary discharge header l3a. It will usually be found desirable to form the primary headers as complete units, and then to braze the shells comprising the secondary headers in place, as indicated at 30, 3|, after the main tubes "in. have been secured to the nipples 32, 33, and after the small tubes iBa have been secured in th openings its and 20a of. the primary headers. With this arrangement the secondary tubes iaa merely pass through the openings 19a, 20a in the walls of ,the primary headers and terminat at that point. Since the escape of a small quantity of steam or condensate from the main headers to the sum iliary ones will not ordinarily be a matter of great importance, the tubes ita may be secured in the openings I90 and 20a by friction alone, or they may be sealed therein as heretofore described. In certain cases it may be preferable to solder one end'of each small tube l8a to one of the main headers l2a or Ma and merely engage its other end by friction with the other of the headers, as this will permit the small tube to expandand contract independently of its main tube Illa without placing any undue strain upon the parts.

this modification the secondary tubes 18b will,

of course, be of similar hairpin shape, and will extend throughout the entire length of the main tubes with their ends passing through the outer walls of the headers i211 and lib for connection to a source of steam 2% on the one hand, and to a condensate drain line 222) on the other. In applying the invention to this or other formsof heaters, independent auxiliary supply and dis-f charge headers, such as 2| and 22 of Fig. 1, may be employed: or the auxiliary supply and discharge headers may be incorporated as parts of the primary headers I20 and Ila in the manner illustrated in Fig. 3.

while the invention has its greatest utility, perhaps, in the light-weight multi-tube, extended surface type of radiator, it may, of course. be embodied in cast-iron radiators of any suitable design, or inplain pipe coil. It is only necessary suitable provision for the supply of steam to 5 them independently of that supplied to the main radiating passages of the device.

Since certain changes may be made in the invention and in its application, all within the skill of the worker in the art, it is intended that the foregoing shall be construed in a descriptive rather than in a limiting sense. i

What I claim is:

1. A heat radiator comprising a steam supply header, a condensate discharge header, a plurality of main transfer tubes having their ends connected to and in open communication with said headers and having outer surfaces which are adapted to transfer heat to air passing over them means for supplying steam to said supply header throttled in accordance with variations in heat load on said main tubes, a plurality of smaller tubes each disposed within and extending lengthwise through one of said main tubes, means for supplying steam to said smaller tubes at substantially constant pressure, and means for draining condensate from said smaller tubes independently of said discharge header.

2. Aheat radiator comprising a primary steam supply header. a primary condensate discharge header, a plurality of main transfer tubes having their ends connected to and in open communication with said primary supply and dischar e headers and having their outer surfaces adapted to transfer heat to air passing over them, a

.secondary steam supply header. a secondary eondensate drain header, a plurality of secondary heat-transfer tubes each disposed within and extending lengthwise of one of said main transfer tubes, and each being connected at one of its ends to said secondary supply header and at its other end to said secondary drain header, means for supplying steam to said primary and secondaryheadersfromacommonsourcasnda controlvalveferreslfletingtbenewofsteamto said primary'supply header'independently of the flow of steam to said secondary supply header and in accordance with variations in the heat load on said main tubes.

3. A heat radiator comprising a primary steam supply header, a primary condensate discharge header, a plurality of main transfer tubes hav ingtheir open ends connected to said primary headers, said main tubes having their outer surfaces disposed in spaced relation and being provided with heat-radiating fins, an auxiliary steam supply header, an auxiliary condensate discharge header, a plurality of secondary heat-transier tubes each disposed within and extendinglengthwise through one of said main transfer tubes, said secondary tubes being substantially smaller in cross-sectional area than said main tubes, and having their open ends connected to'said auxiliary headers, means for supplying steam to said primary supply header throttled in accordance with variations in the heat load on said main transfer tubes, and means for supplying steam to said auxiliary supply header at'substantially constant pressure.

4. A'heat radiator according to claim 3, further characterized'in that said small tubes extend through thewalls of said primary .headersand. are sealed therein, in that said auxiliary headers are independent of said primary headers, and in that the open ends of said secondary tubes are. sealed in said auxiliary headers.

5. A heat radiator according to claim'a, further characterized in that said auxiliary headers are formed integrally with said primary headers.

6. In a heating system, a primary steam supply header, a primary condensate discharge header, a plurality of main transfer tubes disposed in spaced relation with their open ends connected to said primary headers, a line for supplying steam to said primary supply header, means for regu-' lating the flow of steam to such header in accordance with variations in heat load aflecting said main transfer tubes, an auxiliary supply header, an auxiliary discharge header, a plurality of secondary heat-transfer tubes, one disposed within and extending lengthwise through each of said main tubes, said'secondary tubes being substantially smaller in cross-sectional area than said main tubes and having their open ends connected to said auxiliary headers, and means for connecting said auxiliary supply header to said steam supply line at a point ahead of said regulating means whereby steam may be supplied to said secondary tubes independently of that supplied to said main tubes.

7. A bulk material loading machine comprising,

header, a primary condensate drain header, and a plurality of main heat-transfer tubes having their open ends connected to said primary headers; an auxiliary steam supply header, anauxiliary steam condensate header, and a plurality of secondary heat-transfer tubes each disposed within and extending lengthwise of one of said main transfer ations in heat load aflecting said main heattransfer tubes.

MILTON 8. sums.

CERTIFICATE W CORRECTION.

Patent No. 2,365,197. December 19, 19 m; MILTON s. SMITH.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 5, sec

0nd column, line 56 claim 7, for the words "A bulk material loading ma chine comprising" read In a heating system, a primary steam supply--;

and that the said Letters Pater 1t should be read with this correction therein that the sane may conform to the record of the case in the Patent Office,

Signed and sealed this 27m day of March, A. D. 1915.

Leslie Frazer (Seal) Acting Commissioner of Patents 

